The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Don't be in the dark about wild mushrooms

Ten people have been rushed to NSW emergency rooms with mushroom poisoning already this month, prompting a government warning for people to avoid eating wild mushrooms altogether.

It's difficult to tell the difference between edible and poisonous mushrooms and it can be highly dangerous if you eat the wrong one, says Royal Botanic Gardens deputy executive director Dr Brett Summerell.

He advises people to avoid all wild mushrooms.

"Unless you're with an expert who knows each individual species of mushroom very, very well, you should not eat them, because many species are toxic and cause illnesses and in some cases, death," he said.

"We know little very little about the mushrooms in Australia - only 30 per cent have been identified."

He said he's never known such a high rate of poisoning.

NSW Health added its voice to the warning, advising people to stick to mushrooms bought in supermarkets and vegetable stores.

"Some varieties, such as Death Cap mushrooms, can cause death due to kidney and liver damage," said Dr Jeremy McAnulty , Director of NSW Health Protection with NSW Health.

Wild mushroom season has started early thanks to recent wet and humid weather creating ideal growing conditions.